We don't really know yet who does and does not belong to this genus. I link multiple unidentified morphs of this group on the basis of the banding pattern and there usually is some more ornamental variation of the banding across the mid-region of the head. There are some so-called Lineus spp that also have this patterning, and they probably are not Lineus. That genus by itself is a dumping ground.

For many of the difficult invertebrate phyla most of the species are known only from the type locality, often from single specimens. In many cases it seems to be because we haven't looked elsewhere adequately, but reconciling old species descriptions with newly collected material can be very difficult as well. This wish is one reason why I want to switch to Scratchpads, so I can start collecting specimen-based data and have it available for others to use.